This invention resides in the construction and use of catheters for interventional procedures in fields such as cardiology, neuroradiology, urology and gastroenterology.
A major problem in the use of catheters for these procedures lies in the insertion of the catheter through bodily passages to reach the vessel or chamber of interest and the placement of the functional element at the distal tip of the catheter at the site where that element is needed. In some procedures, holding the element at the site while the site moves in response to normal bodily functions such as breathing or a heart beat is also a problem.
Guide catheters are a partial means of solving these problems. Guide catheters are relatively large lumen catheters used to guide smaller diameter catheters such as therapeutic, diagnostic or imaging catheters into bodily passages that are curved or branched. A guide catheter specially designed for a procedure in a coronary artery, for example, is shaped such that when the guide catheter is inserted into the femoral artery and through the aorta of a patient, the curvature of the catheter will place its distal tip inside one of the coronary ostia. Thus, a guide catheter for the right coronary artery is shaped differently than one for the left coronary artery. A guide catheter designed to provide access to a carotid artery is still different in shape. Guide catheters of still other shapes are designed for other bodily passages and regions of interest.
Guide catheters currently available from suppliers occur in a variety of shapes designed for different bodily passages and procedures. Those of skill in the art recognize these different shapes by names such as Judkins Right, Judkins Left, Amplatz Right, Amplatz Left, Bentson, Shepherd Hook, Cobra, Headhunter, Sidewinder, Newton, Sones and others, each formed into a different shape. Most of these different shapes are manufactured in gradations of size and/or curvature to accommodate differences among individual patients.
When a guide catheter is inserted in a patient, its shape is distorted by the connecting passages, such as the aortic arch or the venae cavae. The curves or bends close to the distal end of the catheter retain their shape, however, which is intended to place the opening at the distal end of the guide catheter at the desired location in the vessel or on the vessel wall. Improved control and stabilization of the catheter position is often achieved by anchoring the catheter against an opposing wall, and the ability to do this also depends on the predisposed shape of the catheter.
The dimensions of bodily passages differ from one patient to the next, however, and for proper stabilization and direction of the operating catheter, a guide catheter of the appropriate dimensions must be used. To accommodate this, operating rooms are equipped with a range of sizes of each of the various catheters so that the operator can select the one most suited to the patient, or exchange one already selected for one with a better fit.
Since measurements of these bodily passages cannot be taken prior to insertion of the guide catheter, the physician often relies on visualization devices or techniques incorporated in the catheter body to determine whether the catheter is properly positioned. If the catheter cannot be properly positioned, it must be removed and replaced with one of a different size. This procedure is typically repeated until an acceptable placement is achieved. If this requires many attempts, the cost of the procedure is high due to doctor time and equipment (each catheter is typically disposed of after a single use). Also, the excessive use of contrast media associated with each plavement attempt is not desirable. The risk of infection also rises with multiple insertions since the major potential sources of infection are the patient's own skin contaminants and contamination from the operators, both of which are introduced at the insertion site. Still further, multiple insertions increase the risk of trauma to the vessels receiving the catheters.